San Diego ZooSan Diego, CaliforniaStarted in 1916, this was one of the first zoos that put animals in natural habitats instead of behind bars. Visitors stroll through its 100 acres past lush greenery (6,500 types of plants) to see 4,000 animals comprising about 850 species.Animal Attractions: Monkey Trails and Forest Tales is a mini tropical forest that holds more than 30 species of African and Asian animals, including such endangered monkeys as Schmidt’s guenons and mandrills. Also worth a look is the Lion Camp, home to six lion cubs. Bronx ZooBronx, New YorkOne of the largest city zoos, it contains more than 4,000 animals. Real plants, trees and rocks added to artificial ones make exhibits look part of the natural world. The Bronx Zoo is famous for its conservation work that helps save wildlife around the globe.Animal Attractions: Congo Gorilla Forest, where two troops of lowland gorillas interact over a large territory. The Butterfly Garden is a giant greenhouse holding more than 1,000 North American butterflies that flutter around visitors. Berlin ZooBerlin, GermanyOne of Europe’s biggest zoos, it is also one of the most popular. More than 3 million people visit it each year. One reason is the park’s wide walkways, artificial ponds and beautiful fountains. But the main draw is the nearly 14,000 animals representing nearly 1,500 species-the most in any zoo. Animal Attractions: Miniature hippos frolic in clear-glass pool. The zoo is packed with familiar favorites, such as apes, monkeys, giraffes, African wild dogs and storks, most in large, open spaces. London ZooLondon, EnglandThe greatest zoo in Britain, it houses more than 650 species of animals, including more than 100 that are threatened. It was founded in 1828 as the world’s first zoo created for scientists (Charles Darwin was one) to study animals. Animal Attractions: Among the zoo’s 7,000 animals are such rare ones as the wombat devil, the four-eyed opossum and the bell bird, which makes the loudest noise of any bird. The biggest attraction may be the koalas, which eat eucalyptus leaves zookeepers place on their branches. Taronga ZooSydney, AustraliaOverlooking Sydney harbor, it has amazing views of downtown Sydney. What’s in the zoo is also eye opening: About 340 different species of animals and more than 2,600 individual critters. Animal Attractions: Most interesting is the collection of Aussie animals, including wombats, koalas, kangaroos, platypus and the rare bridled nail-tailed Wallaby. Other unique sights are Leopard Seal (an Antarctic animal that attacks other seals), Australian pelican and a deadly snake called inland Taipan.